Bruh, there are legitimate issues to reproductive health caused by microplastics. That's just a fact. Microplastics are so small they can bypass the blood-testi barrier and disrupt spermatogenesis. They also leech chemicals into the blood that mimic certain hormones, fucking up our endocrine system which has a negative effect on reproductive health as well. There actually are a bunch of people having issues with infertility across the globe, and research shows it is due to microplastics affecting reproductive health, but the current media framing of the argument around microplastics isn't highlighting that specific issue. It is being lumped in with the rest of the issues caused by microplastics and how we don't fully understand just how harmful the build up is to our health overall.
The point is that falling birth rates is a multifaceted issue. It isn't one or the other. It is both medical issues caused by microplastics and socioeconomic stresses.
Also, there isn't a dichotomy between "being told how many kids you can have" and "having their kids starve". Those two things are not mutually exclusive, so they don't have to "take one over the other". No one has to choose between the two nor should they be forced to choose by any body of authority.